The memory devices used on cards such as flash cards in cameras and for transportable storage require voltages that are much higher than the supply voltages (Vcc) available. One such type of memory device today is NAND type flash memory. These types of memory devices require voltages as high as 20 Volts. The Vcc range of operation for these devices is also dropping with every new generation of device. This is in part because end systems are lowering power requirements and this is one way they achieve that goal. In order to supply sufficient voltages for operation of the devices, internal pumps are used to pump the supply voltages up to a suitable operating voltage. However, the internal pumps used for NAND memory devices are increasingly inefficient. For example, at a supply voltage of 1.6 Volts (which is typical in current devices), to generate even 5 to 6 volts, the efficiency of the charge pumps are about 15 percent (%). For the pump to generate 1 mA, it must draw on the order of 7 mA from the supply voltage source.
NAND devices are meant to be stand alone memory devices that need to operate from a single power supply, so manufacturers and assemblers have accepted low efficiency to maintain the standards to which industry expects. Typical pumps used on memory devices are Dixon pumps. These types of pumps have been around for years, and use capacitors and diodes to pump a supply voltage to higher voltages than the internal power supply available. There are other types of pumps that use inductors that are much more efficient. Those types of pumps have efficiencies that approach 80%. Therefore, one can see that such use could make power efficiency of the cards on which the devices are used much greater. However, this requires an external inductor which is not a part of the NAND stand-alone memory.
Since the NAND device needs to be stand alone to comply with industry standards and to allow it to be used across multiple platforms and by multiple manufacturers, the maintenance of standard efficiency pumps and common pin configurations for devices is desirable. However, on the cards used, there may be other voltages available for the card, other systems of the card, or the memory subsystem.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for flash memories and flash memory cards having lower power consumption.